I'm seeing a lot of people posting are looking to run some pretty quick strip times and have a bigger budget than I am really interested in spending on my daily driver.

But that doesn't mean I dont want a turbo hanging off the side of my 6!

I did not build this engine so I don't have all the specs. Its a XE block, mildly ported XF head (oversize valves), comp 10.5:1. All the other parts will be gone if I went for a turbo.

I am looking for a 7-10psi boost (at the manifold) with a powerband between 2000-5000rpm. The car will run straight LPG.

Also the turbo would need to have an internal wastegate because I don't want to spend the extra on an external one if I can avoid it, I'd rather spend the extra on a better turbo. Any suggestions on what would be a suitable brand/model?

The comp will have to be lowered, thats a no brainer, but how low? Can I get away with increasing the volume of the chambers for this amount of boost? Or are dished pistons nessesary?

I was thinking of ditching the carby manifold and going to a XF EFI manifold.

The other question is (and I don't know how many of you will have tried this) what is going to be the best way to run it, blow through or suck through?
I've heard from somewhat dubious mechanics that LPG can't be run suck through because it's too volatile, but aren't people running C16 race fuel in suck through setups? Surely this would be more explosive than LPG?

I only ask because if I can run a suck through setup and use my 425cfm impco carby it would save me about $700. If I have to go blow through I will need to use a gas research setup. I do know Impco's have a diaphram that allows gas to pass and that it gets pushed shut if they are used in blow through setups, but I don't know if they will work in through in suck through.

Being you have LPG you could be safe running your current comp ration with a low boost setup. But to save on blowing gaskets and having an increasing amount of blow by you would want to lower it to around 9.0. If you were to give it more boost i would choose close to 8.0:1, but your talking 20+psi now...

You could buy a second hand RB30 turbo and that will give you your happy power band, plus its an internal wastegate setup.

You can keep the carby setup, but obviously its much easier to tune an EFi engine, but then you need to buy a new programable ecu to suit your needs.

As for the LPG and a suck through setup, reason its not the best idea is because if for some reason the carb stops sucking, the LPG keeps going and gas starts to build up in your plennum (manifold) and kaboom! say goodbye to your carb possibly a gasket or two, and you might even blow your carb through the bonnet (but thats getting a bit extreme).

Personally i would choose the EFi setup, you'll be a lot happier with it, dont forget the custom made exhaust manifold, and the 3" dump + exhaust system, plus injectors etc etc.

I don't want big boost, just a bit more of a kick to see the 6 into the 14's (hopefully) and a bit more fun on the roads each day

I'm only going to use the EFi manifold just because it will work better with the turbo than the carby one, i'm not installing the computer or any injectors (except mabye to plug the holes in the manifold). The LPG will enter the system either through a suck through impco setup, which by the looks of it won't work, or a blow through gas research LPG throttle body setup that sits just like a normal throttle body but mixes gas as well.
Problem being it costs a whole lot more than my impco.
Gas research shows a pic of their suck through setup, but this guy has a much better setup than I am looking to run http://www.gasresearch.com.au/g014.jpg

The exhaust I expected to be one of the most costly parts in the setup. Does anyone make turbo exhaust headers for the 250's? Or am I best to try getting an old pair of headers as well as the RB30 turbo and working the turbo mounts into my current extractors?

If your going to buy a 2nd hand turbo, get a T3 from an RB25. The turbo off the rb30 is a press bearing turbo, and not the most relaible thing in the world, the reason holden had to do a recall on the turbo VL's. Go fot the rb25 turbo, and you be much furthur in front and should only cost about $400 for one. As for the gas, i would not recommend a suck thru system, as all the gas setups i have seen that do this and up with a vacuum behind the carby, and they starve for gas, causes detonation and all the fun things that go with it.
As for the manifold, you should be able to get on knocked up for about $800 at any good engineering shop.
Sounds like a good plan, hope all goes well.

Spending $800 on the headers alone puts me way over budget. Would a stock XF exhaust manifold do the trick? It would not be hard to open one up a bit with a die grinder and weld on the nessesary adaptor for the turbo. It would be about $500 cheaper even with the purchase of a decent die grinder.

Are any of the stock exhaust manifolds any better flowing than others? I have never paid any attention to them at all, straight in the bin and on with extractors!!! Also, can they be flipped upside down? Again I have never bothered to look! (and I don't have one lying around to check!)

And one last question, if I can't use the stock manifold, how many cylinders are needed to create enough flow to power the turbo? If I was to get one exhaust manifold off say a twin turbo V6 300 ZX and modify it to fit onto the back 3 cylinders of my 250. Then have the front 3 cylinders running though my current extractors and joining the two further downstream. Would this setup have enough to spin the turbo properly?

hey xdc351,
i like the sound of what your doing. i know you say your on a tight budget, but how tight? if you dont mind me asking. i'm not really in the position to do something like this at the moment but would be very interested in what it would cost all up. just for future reference. cheers.

hey xdc351,
i like the sound of what your doing. i know you say your on a tight budget, but how tight? if you dont mind me asking. i'm not really in the position to do something like this at the moment but would be very interested in what it would cost all up. just for future reference. cheers.

Paul

I was looking to spend around $3500. with the LPG setup and header fabrication it might just have made it.

I was already going to buy a new cam and lifters, high capacity oil pan and i can get an xf efi manifold for free. Probably $600 worth there.

I was not going to run a intercooler and i figure $500 for other little things and tuning. So all up if your car already had a gas system installed, the cost would be around $3750 all up.

I have instead decidied that the XF is going to be sold to make way for a dead stock AU that a mate is selling, simply because it can tow 2300KG and i need to get a trailer for my V8 XD to do the rounds. Not that I don't trust the XD, but driving to heathcote and back for me is a 400km trip, so I can't really give all to the racing in case I blow something up and can't get home!

I had a stanza with an 1800 turbo that i put GRA on to pass enginering i tried both draw and suck, when it was blow through it was more responsive but had a flat spot we couldn't get rid of, when i changed to draw through it had no flat spot, but a pig to start 'cause the gas had to travel so far.
I eventually ran 20 pounds of boost with no probs.

Im looking at doing the same thing. My car is carb now but i have xe efi out the back. Has anyone used the cast iron headers and made a flange to fit a turbo? Thats what i want. Turbo and intercooler will be from a 740 volvo T. Hopefully have an impco gas mixer and e series converter soon which ive been told can produce around 375hp.

Its all to be done cheaply!

Oh, and lower compression. But maybe just run low boost at the start and leave as standard.

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